StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
11037085
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
2
CommunityOwnedDate
CreationDate
2012-06-14T16:09:45.513
FavoriteCount
0
LastActivityDate
2018-08-19T20:43:49.483
LastEditDate
2018-08-19T20:43:49.483
LastEditorUserId
1320535
OwnerUserId
1320535
ParentId
11036989
PostTypeId
2
Score
169
ViewCount
0
LastEditorDisplayName
text
Body
Replacing all zeroes to NA: <pre><code>df[df == 0] <- NA </code></pre> Explanation 1. It is not <code>NULL</code> what you should want to replace zeroes with. As it says in <code>?'NULL'</code>, <blockquote> NULL represents the null object in R </blockquote> which is unique and, I guess, can be seen as the most uninformative and empty object.1 Then it becomes not so surprising that <pre><code>data.frame(x = c(1, NULL, 2)) # x # 1 1 # 2 2 </code></pre> That is, R does not reserve any space for this null object.2 Meanwhile, looking at <code>?'NA'</code> we see that <blockquote> NA is a logical constant of length 1 which contains a missing value indicator. NA can be coerced to any other vector type except raw. </blockquote> Importantly, <code>NA</code> is of length 1 so that R reserves some space for it. E.g., <pre><code>data.frame(x = c(1, NA, 2)) # x # 1 1 # 2 NA # 3 2 </code></pre> Also, the data frame structure requires all the columns to have the same number of elements so that there can be no "holes" (i.e., <code>NULL</code> values). Now you could replace zeroes by <code>NULL</code> in a data frame in the sense of completely removing all the rows containing at least one zero. When using, e.g., <code>var</code>, <code>cov</code>, or <code>cor</code>, that is actually equivalent to first replacing zeroes with <code>NA</code> and setting the value of <code>use</code> as <code>"complete.obs"</code>. Typically, however, this is unsatisfactory as it leads to extra information loss. 2. Instead of running some sort of loop, in the solution I use <code>df == 0</code> vectorization. <code>df == 0</code> returns (try it) a matrix of the same size as <code>df</code>, with the entries <code>TRUE</code> and <code>FALSE</code>. Further, we are also allowed to pass this matrix to the subsetting <code>[...]</code> (see <code>?'['</code>). Lastly, while the result of <code>df[df == 0]</code> is perfectly intuitive, it may seem strange that <code>df[df == 0] <- NA</code> gives the desired effect. The assignment operator <code><-</code> is indeed not always so smart and does not work in this way with some other objects, but it does so with data frames; see <code>?'<-'</code>. 1 The empty set in the set theory feels somehow related. 2 Another similarity with the set theory: the empty set is a subset of every set, but we do not reserve any space for it.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POReplace all 0 values to NA
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USJulius Vainora
UserOwnerUserId
1. USJulius Vainora
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POReplace all 0 values to NA
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTAcceptedByOriginator
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.